27 FEBRUARY 1915, Page 24

The questions of the origin of "dew-ponds," and of the

manner of their action, have long supplied opportunities for

iontroversy. Mr. Edward A. Martin in his Dow-Ponds: Victory, Observation, acid Experiment (T. Werner Laurie, 6s.) describes the results of a three years' series of experiments made by him with the help of a grant from the Royal Society. The conclusion which he reaches is that dew has little to do with the replenishment of the ponds, which, be maintains, is effected mainly by the precipitation of the fogs and mists that occur so commonly upon down-lands.